Android Question hudge narrow picture - how to get the width ?

peacemaker · Sep 8, 2017

Hi, All

If used some image that is big too much to load directly (as out of memory error) - how to get image dimensions ?
WebView is able to load and show this big picture, but .... it needs to know what max lendth (width) for scrolling...

peacemaker · Sep 9, 2017

SOLVED myself:

1) Webview with JavascriptInterface
2)

B4X:

'first picture load (huge picture 26000 x 250 pixels, 8bit color)
wv.LoadHtml("<html><body> <img src=" & QUOTE & "file://" & Notes & QUOTE & " id='img1' ></body></html>")

....

Sub wv_PageFinished (Url As String)
    If Flag = 0 Then  'first picture load
        Flag = 1
        Do_JS("document.getElementById(" & QUOTE & "img1" & QUOTE & ").naturalHeight")
        wait for Show_result(res As String)
        ImgHeight = res
        Rate = hsv.Height/ImgHeight  'hsv is Horizontalscrollview containing the Webview
        Do_JS("document.getElementById(" & QUOTE & "img1" & QUOTE & ").naturalWidth")
        wait for Show_result(res As String)
        ImgWidth = res
        hsv.Panel.Width = ImgWidth * Rate
        wv.Width = ImgWidth * Rate
        pnl.Width = ImgWidth * Rate   ' pnl is a panel over Webview to prevent vertical swipes over Webview - that would lead to the app crash.
'second reloading picture when the webview size it pre-set
        wv.LoadHtml("<html><body> <img src=" & QUOTE & "file://" & Notes & QUOTE & " id='img1' ></body></html>")
    Else  'second picture loading
        ProgressDialogHide    'finish second picture loading
        Log("stop")
    End If
End Sub

Sub Do_JS (JS As String)
    Dim Javascript As String
    Javascript="B4A.CallSub('Process_HTML', true, " & JS & ")"
    WebViewExtras1.executeJavascript(Javascript)
End Sub

Sub Process_HTML(Html As String)
    '   This is the Sub that we'll get the web page to send it's HTML content to
    '   Log may truncate a large page so you'll not see all of the HTML in the log but the 'html' String should still contain all of the web page HTML
    CallSubDelayed2(Me, "Show_result", Html)
End Sub

'and the main - set zoom to see the picture maximally filling the screen
Sub lblAction_Click
        WebViewExtras1.SetInitialScale(100 * Rate)
        hsv.Visible = True

End Sub

Android Question hudge narrow picture - how to get the width ?

peacemaker

Expert

peacemaker

Expert

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